Gets or sets the extent (from -1 to 1) at which to end rendering the needle, measured from the center of the gauge. Values further from zero than 1 can be used to make this extend further than the normal radius of the gauge.
Target Platforms: Android 4.4+, iOS 8+
Development Environments: Visual Studio 2015+, Visual Studio for Mac Preview, Xamarin for Visual Studio 4.2+
